JP2001036591A - Wireless electromagnetic transmission method for data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that attains transmission of data at a high transmission rate independently of the electric field strength of the signal data to be transmitted and that is available for signal data including a DC voltage component depending on contents of the signal data. SOLUTION: This method is a method that electromagnetically transmits data wirelessly. The data are binary signals transmitted from a transmitter as amplitude-modulated signals. A receiver receives the signals and converts the signals into rectangular signals 43 by means of an adjustable comparator threshold value 42 in this wireless electromagnetic transmission method. This method holds the width (b) of the demodulated pulse signals to be a prescribed target value at least partially by varying the comparator threshold value 42 to trace the pulse width (b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting data electromagnetically by radio, wherein the data is a binary signal transmitted as an amplitude-modulated signal from a transmitting device and received by a receiving device. And a transmission method which is converted into a rectangular signal via an adjustable comparator threshold.

[0002]

2. Description of the Related Art In order to transmit data wirelessly, data as a binary signal is often converted into an amplitude-modulated signal. This converted signal sometimes has a considerable transient post-oscillation period due to the characteristics of the transmitting device, so that the transmitted signal is decompressed and may overlap if the data transmission rate is too high. It can happen. This is particularly likely to occur in a wireless identification device having a transmitter provided with a high Q antenna resonance circuit.

[0003] A received signal is converted into a rectangular signal upon demodulation via an input threshold. To this end, the received signal is directed to a comparator having an adjustable comparator threshold. This comparator threshold follows the DC voltage component of the demodulated signal in a general manner. However, such a method of adjusting the comparator threshold is suitable only for a bit code method having no DC voltage.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to enable high-speed data transmission without depending on the electric field strength of a signal to be transmitted, and to be used for a signal having a DC voltage component depending on the signal content. It is to provide a method.

[0005]

The above object is achieved by keeping the pulse width of the demodulated signal at a predetermined target value, at least partly, by following a comparator threshold value. The comparator threshold can also be tracked by signals of the present invention in the presence of a DC voltage.
The data transmission speed can be increased by following the comparator threshold.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a first embodiment of the present invention, a target value of a pulse width of a demodulated signal is set to be constant at least for each part. This is advantageous in signals where the spacing between the pulses is modulated by the information to be transmitted.

[0007] The pulse width of the demodulated signal can be controlled to a target value by using a comparator threshold as an operation amount. By controlling, the comparator threshold can be adapted very flexibly.

In another embodiment of the present invention, a signal is provided to a peak value rectifier to cause a comparator threshold to follow the peak value in a ratio. Further advantageously, the time constant of the peak rectifier is selected for this purpose in the region of the expected maximum pulse interval of the signal. If the time constant is too small, the fluctuation of the comparator threshold will be large. For example, the comparator threshold can always be adjusted to half the peak value formed in the rectifier.

An envelope of the signal can be formed for demodulation. In this way, demodulation of the signal can be performed relatively easily. Alternatively, the oscillations of the signal that exceed the comparator threshold can be counted, thereby determining a measure for the pulse width. However, this requires that the microcontroller operate fast enough with respect to the carrier frequency.

In a further embodiment of the method according to the invention, the pulse width of the demodulated signal is detected, compared to a target value, and the comparator threshold is followed depending on the result of the comparison.

For this purpose, the comparator threshold value is continuously followed. Alternatively, the first received pulse of the signal at the start of transmission is guided to a comparator threshold that continuously increases from a predetermined minimum value, and the width of the resulting pulse is detected, and the width of the resulting pulse is detected. Detect the value for the comparator threshold applied to the next received pulse, set the comparator threshold to a new value before receiving each new pulse of the signal to be received, and then set the pulse of the next received signal. To the newly set comparator threshold for demodulation and detection of the next pulse width. Then, the new value is detected based on the width of the preceding pulse.

[0012] The step-by-step tracking of the comparator threshold can be easily realized in a software program, and it works even if the computing power of the microcontroller to be executed is lower than that required for continuous control. The detection of the comparator threshold to be set next is performed based on a characteristic map or a control function. From this function, the pulse width can be extracted depending on the signal level.

In order to carry out the method according to the invention, another embodiment is configured as follows. That is, the received signal is supplied in parallel to a first comparator and a device for following a comparator threshold, and the output signal of the first comparator is guided to an envelope filter and a second comparator having a fixed threshold. It is configured to convert to a rectangular signal. In this way, the signal pulses can be clearly separated from each other even when the data transmission speed is high, and can be easily identified by the microcontroller.

[0014]

FIG. 1 shows a signal pulse 1, which is a signal pulse transmitted from a transmitting device after modulating a carrier with a rectangular pulse 2. FIG. After receiving the signal pulse 1 at the receiver, the envelope 3 of the signal pulse is formed. The envelope 3 is led to a comparator threshold 5 to form a rectangular pulse 4.

FIG. 2 shows envelopes 21 of various levels of signals.
22, 23 are shown. By demodulating via a fixed comparator threshold 5, the envelopes 21, 22,
23 generates rectangular signals 24, 25 and 26. The higher the signal level, the higher the demodulated signals 24, 25,
The 26 rectangular pulse intervals are becoming increasingly narrower. In the case of the signal 23 having the highest level, the pulse cannot be distinguished.

In the block circuit diagram shown in FIG. 3, a signal 32 received from a transmitting device 31 is amplified by an amplifier 33,
A first comparator 34 having an adjustable threshold and a peak value rectifier 35 are provided. The peak value rectifier 35 forms a peak value curve 32a of the signal 32, which is used by the first comparator 34 to follow the comparator threshold.
Supplied to Comparator 34 forms a high-frequency rectangular signal 32b, which is converted via an envelope generator 36 into an envelope curve 32c and, finally, a rectangular signal via another comparator 37 having a fixed threshold. It is converted to a signal 32d. The rectangular signal 32d can be further processed by a microcontroller.

FIG. 4 shows a signal 41 which, via a continuously tracked comparator threshold 42, receives a rectangular signal 4.
Converted to 3. The comparator threshold 42 is followed so that the width b of the generated rectangular pulse 43 is substantially constant.

To control the comparator threshold stepwise, a microcontroller 52 can be used as shown in FIG. The received signal 32 is converted to an envelope demodulator 5
0 to an envelope signal 53. This envelope 53
Is converted into a rectangular signal 54 using the comparator 51.
The comparator threshold is controlled by a subsequent microcontroller 52 according to FIG.

In FIG. 6, the tracking of the comparator threshold 42 'takes place stepwise between the individual pulses of the signal 41. At the start of data transmission, the comparator threshold is ramped up from a minimum value 61, the first received signal pulse 62 is demodulated via such a rising comparator threshold, and converted to a first rectangular pulse 63. I do. Comparator threshold 4 according to the width of rectangular pulse 63
Determine the initial value of 2 'and set the comparator threshold to this value before the next signal pulse 64 occurs.

A new set value of the comparator 42 'is determined from the width of the rectangular pulse 43' formed as follows. That is, it is determined that the pulse width of the rectangular signal 43 'remains substantially constant. The comparator threshold 42 'is always set to this new value before each new pulse of the signal 41 occurs.

[Brief description of the drawings]

FIG. 1 shows a signal pulse of a signal transmitted using the method according to the invention.

FIG. 2 illustrates the different effects of different levels of signals when the comparator threshold is fixed.

FIG. 3 is a block diagram of the signal processing when implementing the method according to the invention for continuously following the comparator threshold;

FIG. 4 is a diagram showing a signal demodulated by a continuously tracked comparator threshold.

FIG. 5 is a block diagram showing signal processing for following a comparator threshold stepwise.

FIG. 6 is a diagram of a signal demodulated with a stepped tracked comparator threshold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal pulse 3 Envelope 5 Comparator threshold 31 Transmitter 33 Amplifier 35 Peak value rectifier 36 Envelope generator 37 Comparator 50 Envelope curve demodulator 51 Comparator 52 Microcontroller

 ────────────────────────────────────────────────── ─── Continued on the front page (71) Applicant 390009416 Kruppstrabe 105, Franckfurt am Main, BRD (72) Inventor Christopher Jiefels Germany Hanau Konrad-Adenauer-Strasse 9 (72) Inventor Reinhold Berberg Germany Frankfurt Keller-Bornstrasse 4

Claims (11)

[Claims] 1. A method for wirelessly transmitting data as a binary signal wirelessly, said data being transmitted from a transmitting device as an amplitude modulated signal, received by a receiving device, and adjustable. In the data transmission method, which is converted into a rectangular signal via a suitable comparator threshold, the pulse width (b, d) of the demodulated signal (43, 43 ′)
b ′) is kept at least stepwise at a predetermined target value by following the comparator thresholds (42, 42 ′);
A data transmission method characterized by the above-mentioned. 2. The method according to claim 1, wherein the target value of the pulse width (b, b ′) of the demodulated signal (43, 43 ′) is set to be constant at least for each part. 3. The method according to claim 1, wherein the pulse width of the demodulated signal is adjusted to the target value by using a comparator threshold value as an operation amount. 4. A signal (32) for peak value rectification (35).
4. The method according to claim 1, wherein the comparator threshold is made to follow the peak value (32a) in a ratio. 5. The signal envelope for demodulation (32c).
5. The method according to any one of claims 1 to 4, wherein 6. The method according to claim 3, wherein the oscillations of the signal exceeding the comparator threshold are counted, thereby determining a measure for the pulse width. 7. A pulse width (b, b ′) of the demodulated signal (43, 43 ′) is detected, and the pulse width is compared with a target value. 42 ')
4. The method of claim 3, wherein 8. The method according to claim 1, wherein the comparator threshold is continuously tracked. 9. The first received pulse (52) of said signal (41) at the start of transmission leads to a continuously increasing comparator threshold (42 ') from a predetermined minimum value (51), resulting in The method of claim 7, wherein the width of the pulse (53) is detected and a value for a comparator threshold (42 ') applied to the next received pulse (54) is determined therefrom. 10. A comparator threshold (42 ') before each new pulse of the signal to be received (41) is received.
Is set to a new value, the new value is detected based on the pulse width (b ′) of the preceding pulse, and the pulse received next to the signal (41) is demodulated and the next pulse width is detected. 8. The method according to claim 7, which leads to a newly set comparator threshold (42 '). 11. The signal (32) received is supplied in parallel to a first comparator (34) and a device (35) for following a comparator threshold, and an output signal (32) of said first comparator (34). 32b) with the envelope filter (3
6) and a second comparator (37) having a fixed threshold
11. The method according to claim 1, wherein the signal is guided to a rectangular signal (32d).